The invention relates to a gas burning smokers' lighter comprising a casing; a fuel reservoir with a valve which controls the discharge of fuel gas through a burner nozzle located within the casing; an electrical spark ignition system for igniting fuel gas leaving the burner nozzle; and manually operated actuating means causing the burner valve to open and the ignition system to operate. Such a lighter is hereinafter referred to as of the kind described.
Such lighters are subject to two important problems, which have not been solved wholly satisfactorily in the past. The first problem is the need to provide adequate protection for the delicate burner nozzle, burner valve, and sparking electrode(s). Such protection is important as experience shows that lighters frequently require maintenance because of an accumulation of foreign material adjacent to these parts or damage to these parts. The second problem is the difficulty in igniting the fuel gas first time upon operation of the ignition system. This arises because an electrical spark ignition system, such as a piezoelectric ignition system, usually produces a single spark for a short duration and the fuel gas/air mixture must be within a limited range of proportions in the immediate proximity of the spark if the gas is to be ignited. The difficulty is that the natural solution to the first problem is to enclose the burner nozzle and associated parts within a hollow upper part of a completely closed casing but this exacerbates the second problem by preventing the access of ignition air to the ignition zone adjacent to the burner nozzle until the casing is open to reveal the burner nozzle.
One solution has involved a so-called "fully automatic" lighter in which a finger piece actuating member forming a part of the closed casing is engaged and physically moved relatively to the rest of the casing against spring action. The movement of the actuating member itself reveals the burner nozzle and provides access for ignition air to the burner nozzle, the movement also causing opening of the burner valve and operation of the ignition system. When the actuating member is released, it makes a return stroke under the spring action so as to close the burner valve and casing. Such lighters suffer from the drawback that the speed at which the actuating member is moved by the user determines whether the access for ignition air has been sufficiently long before the ignition system is operated for the gas and air to have formed an ignitable mixture when the ignition spark is discharged. Also, and more importantly, the movement of the actuating member must necessarily be continued until the ignition system is operated, and in practice slightly beyond this point to ensure that the ignition system is operated in spite of any tolerances in the parts. It follows that the trailing end of the actuating member which usually forms the burner cover when closed and a boundary of the air inlet passage and flame aperture when open, is moving adjacent to and disturbing the gas/air mixture in the ignition zone right up to the moment at which the ignition spark is discharged. The operation of the known fully automatic lighters in thus uncertain and subject to the vagaries of the user, and they will not operate satisfactorily irrespective of the manner in which they are operated. As a result, fully automatic lighters have a reputation for not providing first time ignition with sufficient reliability.
Another solution involves the so-called "box-type" lighter in which the casing incorporates a hinged lid which is swung upwards or laterally to uncover the burner nozzle, and usually also to open the burner valve. However, the lid is a part vulnerable to damage and repair, is expensive and replacement thereof has involved replacement of the whole casing. Even if the swinging of the lid is responsible for opening the burner valve, this preliminary operation has to be followed by transference of the operator's thumb through an appreciable distance to a further actuating member for operating the ignition system and this has resulted in a somewhat tedious and clumsy manipulation of the lighter, as well as a waste of fuel gas prior to ignition. Further, in cases in which the lid has been swung upwards to uncover the burner nozzle, the lid has remained in an upwardly projecting position alongside the flame and has impeded the use of the flame. This solution, as that involving fully automatic lighters, is expensive in that the lid of the box type and the actuating member of the fully automatic lighter, which is displaced to uncover the burner nozzle, has needed to be large enough not only to cover the burner nozzle but to receive the user's thumb for displacement. Consequently the displacement part has provided such a relatively large proportion of the lighter casing that it has had to be embellished often in a similar manner to the rest of the casing and, being a separate part, this has involved two separate embellishment steps. If the embellishment involves any design which carries across the interface of the two parts, the embellishment becomes an even more expensive operation.